Nutria (Myocastor coypus Molina)

Nutria are an invasive species of rodent that are threatening the health of marine and freshwater habitats in the Pacific Northwest. Nutria spend much of their time in the water and are highly adapted to a semi-aquatic existence.

What to they look like?

Often mistaken for a beaver, nutria are smaller (about the size of a cat). Adults weigh less than 20 pounds and are about 2 feet long. They have dark fur, but not as dark as a beaver. Their tails are thin, round, and pointed at the tip, unlike a beaver’s tail, flat and broad.

What seems to be the problem?

Using their large front teeth, nutria gnaw voraciously on the roots of fresh and saltwater marsh plants, which are important habitat for many native fish and waterfowl. Their preferred diet consists of young aquatic plants in both salt and freshwater environments.

In Skagit County, nutria have been burrowing into dikes, potentially undermining the flood control structures that protect much of Skagit Valley’s farm fields, homes and infrastructure. Farmers are understandably worried about their crops that nutria might consume.

What do Nutria eat?

Nutria eat about 25% of their body weight daily. They are opportunistic feeders with an extremely varied diet. In marsh habitats, nutria forage directly on the vegetative root mat, which can result in an ‘eat out‘ (an area devoid of vegetation as soil is washed away). Nutria also feed on crops, lawn grasses, and ornamental plants adjacent to aquatic habitats.